1. Technical Field
The present invention relates to a wiper blade assembly for wiping a windshield of a vehicle actuated by a wiper arm, and more particularly, to a wiper blade assembly that has a plurality of auxiliary beams each having a given initial curvature and providing a given elastic force, thereby uniformly applying the load applied from the wiper arm to the end portions of a wiper blade. The plurality of auxiliary beams are rotatably mounted on a guide beam, thereby substantially enhancing compliance with variations in the curvature of the windshield surface and treatment thereof, and further improving the degree of freedom according to the curvatures of the windshield surface.
2. Background of the Related Art
A wiper is adapted to come into close contact with a curved windshield of a vehicle so as to remove foreign materials that have accumulated on the surface of the windshield. There are two methods for facilitating contact between the wiper and the curved windshield surfaces. The first method is carried out by distributing the forces applied by a wiper arm to the wiper blade, and the second method is carried out by providing an initial curvature to the wiper blade assembly.
Generally, the wiper using the second method is called a flat wiper. The present invention relates particularly to flat wiper blade assemblies. If the wiper blade assembly has a given elastic force by the formation of an initial curvature thereof, it can be brought into close contact with the windshield of the vehicle, without having an additional structure for distributing the load applied from the wiper arm thereto. Advantageously, the configuration of such a blade is simplified.
Many conventional wiper blade assemblies include a flexible elongated wiper blade having a given elastic force that elastically contacts a vehicle windshield, a guide beam coupled to the flexible elongated wiper blade, having a given initial curvature to transfer the load applied from a wiper arm to the wiper blade, thereby allowing the wiper blade to come into direct contact with the vehicle windshield, and rail springs adapted to maintain the wiper blade in a predetermined shape.
Such conventional wiper blade assemblies are configured with the wiper blade and the guide beam extending longitudinally and the wiper blade is brought into close contact with the vehicle windshield by means of the elastic force provided by the formation of the initial curvature of the guide beam and the load applied from the wiper arm.
In these conventional wiper blade assemblies, the guide beam extends in a longitudinal direction with respect to the wiper blade, but the wiper arm is connected to the central portion of the guide beam. However, the load applied from the wiper arm is not distributed uniformly to the guide beam and is applied to only the central portion thereof, resulting in application of a relatively small load from the wiper arm to the end portions of the guide beam.
Therefore, the end portions of the guide beam do not effectively perform their intended function of allowing the wiper blade to come into close contact with the windshield of the vehicle. Thus, if the vehicle windshield has a relatively large curvature, the end portions of the wiper blade remain spaced from the surface of the windshield.
On the other hand, if the guide beam has a relatively large curvature, so as to allow the end portions of the wiper blade to come into close contact with the windshield, the stiffness of the guide beam may prove to be undesirably low, such that the region between the central portion and the end portion of the guide beam is spaced apart from the surface of the vehicle windshield. To the contrary, if the chosen stiffness of the guide beam is high, the wiper blade is not brought into uniform contact with the surface of the windshield.